Birnbaum–Saunders sample selection model

The sample selection bias problem occurs when the outcome of interest is only observed according to some selection rule, where there is a dependence structure between the outcome and the selection rule. In a pioneering work, J. Heckman proposed a sample selection model based on a bivariate normal distribution for dealing with this problem. Due to the non-robustness of the normal distribution, many alternatives have been introduced in the literature by assuming extensions of the normal distribution like the Student-t and skew-normal models. One common limitation of the existent sample selection models is that they require a transformation of the outcome of interest, which is common R+-valued, such as income and wage. With this, data are analyzed on a non-original scale which complicates the interpretation of the parameters. In this paper, we propose a sample selection model based on the bivariate Birnbaum–Saunders distribution, which has the same number of parameters that the classical Heckman model. Further, our associated outcome equation is R+-valued. We discuss estimation by maximum likelihood and present some Monte Carlo simulation studies. An empirical application to the ambulatory expenditures data from the 2001 Medical Expenditure Panel Survey is presented.     

Window strikes: bird collisions in a Neotropical green city

Urban Ecosystems - Window strikes are among the most worrisome causes of bird mortality. Being responsible for billions of avian deaths, bird-window collisions have been widely studied in the US...     

Production layout improvement in emergency services: a participatory approach

Volunteer fire department is a service that responds emergency situations in places where there are no military emergency services. These services need to respond quickly, because time is often responsible for the operation success besides work environment and setup time interfere with the prompt response to these calls and care efficiency. The layout design is one factor that interferes with the quick setup. In this case, the spaces arrangement can result in excessive or unnecessary movements; also the equipment provision may hinder the selection and collection of these or even create movement barriers for the workers. This work created a new layout for the emergency assistance service, considering the human factors related to work through the task analysis and workers participation on the alternatives of improvement. The results showed an alternate layout with corridors and minimization of unusable sites, allowing greater flexibility and new possibilities of requirements.     

Application of ergonomics principles in underground mines through the Occupational Safety and Health Management System--OSHMS OHSAS 18.001:2007

The underground mining activity is regarded as one of the activities that cause most accidents, deaths and illnesses in the world, highlighting the coal mines. This study examined how ergonomics principles can help improve this environment, reduce the number of accidents and occupational diseases, train and empower workers and leaders and humanize the activities of the duty cycle of an underground mine. For this, it was developed a conceptual model of safety managing and health at work for the underground mining through the incorporation of ergonomics principles in the Occupational Safety and Health Management System and OHSAS 18001 (2007). The elaboration of the model was based on analysis of the environments and stages of work in underground mines and the PDCA cycle to ensure continuous improvement.     

Colour, vision and ergonomics

This paper is based on a research project - Visual Communication and Inclusive Design-Colour, Legibility and Aged Vision, developed at the Faculty of Architecture of Lisbon. The research has the aim of determining specific design principles to be applied to visual communication design (printed) objects, in order to be easily read and perceived by all. This study target group was composed by a selection of socially active individuals, between 55 and 80 years, and we used cultural events posters as objects of study and observation. The main objective is to overlap the study of areas such as colour, vision, older people's colour vision, ergonomics, chromatic contrasts, typography and legibility. In the end we will produce a manual with guidelines and information to apply scientific knowledge into the communication design projectual practice. Within the normal aging process, visual functions gradually decline; the quality of vision worsens, colour vision and contrast sensitivity are also affected. As people's needs change along with age, design should help people and communities, and improve life quality in the present. Applying principles of visually accessible design and ergonomics, the printed design objects, (or interior spaces, urban environments, products, signage and all kinds of visually information) will be effective, easier on everyone's eyes not only for visually impaired people but also for all of us as we age.     

A practical approach to the assesment of manual handling equipment for cargo: multinational abrasives in Brazil

The Manual Handling of Loads is an activity present in virtually all production system, when developed without ergonomic principles of design and sizing can generate several instances of discomfort and musculoskeletal disorders. This work was carried out to measure, set limits and risks and guide specifications for the cargo handling carts in a specific company, tracing the anthropometric profile of the productive population and performing a quantitative evaluation of forces and design models of cars used in the company.     

Evil Tidings: Are Reorganizations more Successful if Employees are Informed Early?

Organizations represent deliberately designed social contexts that are characterized by multi-level hierarchies. Interests and opportunity structures at each level usually do not overlap. We suggest that one of the reasons why intentional change efforts often fail to reach their objectives is because they are likely to trigger competing social mechanisms at different levels of the hierarchy. In order to illustrate this argument, we analyze the consequences of timely communication of planned organizational changes on perceived success of reorganizations. Two competing mechanisms are derived and tested with data from a telephone survey (carried out in 2003), among a sample of n = 412 Dutch business organizations that performed a reorganization. The commitment perspective predicts that early announcement of reorganization plans to middle management increases the likelihood of reorganization success, since it increases commitment and empowers middle management. The influence mechanism predicts that early information of non-managerial employees decreases the likelihood of reorganization success, because it enables employees to use the information to their own advantage, anticipate on the strategies of management, and organize opposition against the plans. We found that timely communication with middle management indeed increases chances for success, whereas timely communication with employees correlates with reorganization failure. However, not communicating with employees has an even stronger negative effect on reorganization success. No evidence could be found for our argument that the severity of the reorganization’s expected negative effects on the workforce moderates both mechanisms.     

The emancipation of disability studies in Portugal

Despite the interest of the social sciences in issues of exclusion and inequality, the question of disability, as a key issue of reflection, remains absent from many academic areas. The emergence of disability studies owes much to contexts in which the activism of disabled people has revealed the structural conditions that oppress and neglect experiences of disability. Bearing in mind the specific features of the Portuguese socio-political environment, two lines of inquiry are developed in this text. Firstly, what are the challenges faced by Portuguese academics in making disability a central issue, enabling it to confront the silencing of the voices and experiences of disabled people in society? Secondly, how important is it for research to engage with an ethical and political paradigm that supports the rights of disabled people?     

Functional connectivity in urban landscapes promoted by <Emphasis Type="Italic">Ramphastos toco</Emphasis> (Toco Toucan) and its implications for policy making

The scarcity of green areas in urban landscapes hinders connectivity among sites reducing the flux of organisms and seed dispersal. Ramphastos toco is an effective plant disperser in tropical landscapes, playing an important role in conserving plant connectivity. In this study we combined two methods of landscape connectivity analysis, in a way not yet explored, to assess the potential contribution of Ramphastos toco to enhancing connectivity among urban vegetation patches. We used spatial modeling techniques to evaluate least cost routes, or those that facilitate bird movement through green urban areas, in Belo Horizonte, a city in Southeast Brazil. We also assessed the relative importance of forest patches for conserving both bird and seed dispersal fluxes using the integral index of connectivity. The resulting least cost route of greater accessibility for the species included in its course an important forest patch under environmental licensing for the construction of a residential condominium. The number of green urban areas covered by forest, of highest habitat quality for the species, summed to 155 patches. Of this total only 5.2% were relevant for regional connectivity, while the four most important patches are targeted by the city’s expansion plans. Ramphastos toco is an effective connector for tropical green urban areas given its adaptability, wide range of movement and seed dispersal effectiveness. We emphasize the need for incorporating ecological knowledge and the prioritization of green areas into city planning, since current expansion projects jeopardize forest patches that are crucial to the functional connectivity of the urban landscape.